Can anyone tell me if making butter undergoes a physical or chemical change? Or both?

As far as I know, only a physical change. The fats in the cream do not alter chemically (as in their chemical formula do not change) but they form weak bonds as they are slammed up against each other and intertwine like a bunch of yarn clumping together into a tangle. Some water (as well as some of the water soluble components of cream) gets stuck in the tangle and the rest puddles outside of the ball of butter. If you melt the butter gently it doesn't alter it chemically either since it simply untangles and flows more freely. When the heat is removed it retangles and slows down to form butter again.

Of course, technically all of this counts as chemical changes since phase changes and precipitating molecules from a suspension are all considered chemical changes, but I think I answered your question as you'd expect.

Most of these posts are concerned with how to make butter at home, but I think why one might want to should be addressed. Raw milk, unpastuerized and unhomogenized , has "good" bacteria as well as enzymes to digest the food. Without these 2 components, it may be or may not be "safe" from spoilage but it has very little health benefit. Unless one is just curious about the process of what our ancestors did to make butter(which would have been raw and healthy) there is little reason to make your own butter from pastuerized cream. You can buy many fine products from health food stores, etc. If you are searching for better health, sustainable living, boosted immune systems, making butter that retains the symbiotic realtionship with man of "good" bacterias as well as the enzymes to digest it, makes good sense. There are MANY web articles about pastuerization and homogenization that are quite detailed to explain more, but after reading the different comments here, I felt the need to clarify this point.

Does anyone know if using evap milk is an acceptable "meet in the middle" option? My boy wants to do this ASAP, we live way out of town (but don't have cows, darn it), and I know it would be near to impossible to start with whole milk. But what about evap milk? I've always been told evap milk is just concentrated milk, i.e. certain amount of the liquid has been removed. But can you make butter with it? Is this even a reasonable question?

We HAVE made butter w/heavy cream, which was delightful/tasty/fascinating, hence the boy's desire to do so again. Being 12, he wants to do it now, of course. Any advice?

Wonderful! My son has been asking me to help him make butter for quite a while. Googled "making butter" and found this website and your recipe. We did it with a hand mixer and it came out perfect and delicious. THANKS!!!

If I were to put heavy cream in a tuperware bowl and tell my little 2nd cousins to shake it, how long would it have to sit and what other steps would be used in this process?

How long would it have to sit? Or how long would they have to shake it? I don't know the answer to either of those questions - I'm not sure why it would need to sit unless you were doing the step of adding buttermilk to the mixture to provide some more flavor/tang. In that case, just let it sit at room temp. for about twelve hours before having your cousins shake out their excess energy. As to how long it takes before butter forms - that really depends on how vigorous your cousins shake. I'd guess between 15 min. to an hour.

Just a thought for people who have not studied or thought about the influence and the rhythm of nature according to the moon, there is a time to gather milk and churn for buttermaking and a time not to. I refer you to work by Johanna Paungger and Thomas Poppe...I can't find the dates in the books right now but have them noted at home. Email me at myrick@middlebury.edu if you are interested. ("Guided By the Moon" and "Moontime".)

I have made plenty of butter from our own cows' milk and goats' milk but not for a while so the timing doesn't stick in my mind (too much stuff crammed in there!)

Just a thought for people who have not studied or thought about the influence and the rhythm of nature according to the moon, there is a time to gather milk and churn for buttermaking and a time not to. I refer you to work by Johanna Paungger and Thomas Poppe...I can't find the dates in the books right now but have them noted at home. Email me at myrick@middlebury.edu if you are interested. ("Guided By the Moon" and "Moontime".)

I have made plenty of butter from our own cows' milk and goats' milk but not for a while so the timing doesn't stick in my mind (too much stuff crammed in there!)

I meant to say cream instead of milk...of course I let the cream rise to the top of the milk and use that. What is the sense of churning your own butter if you use dead (pasteurized) cream? Healthwise, makes no sense. You can, though, control the quality of your product if you purchase milk from organic or naturally raised animals instead of taking the commercial product of factory-raised animals...poor thangs! If you can't afford organic, at least buy your fats, then meats that are organic as pesticides cling to fats and your brain needs/uses fats, you can probably figure out the rest yourself. In my opinion, what the USDA says is good is probably bad and what they say is bad is likely good. There are exceptions to every rule...!

When I said "find the dates" I meant signs, the moon passes through the signs of the zodiac and they influence the butter making, breadmaking, planting, fishing, etc. For example, today, November 11th of '08 the moon is passing through Aires. The moon is waxing and it will be full in a couple days.
Again, I may not find this site again and will forget about it (the stuffed brain syndrome) so if you want to dialogue with me, myrick@middlebury.edu. Later.